Conventional insulin therapy is considered to be inadequate for the restoration of normoglycemia sufficient to prevent the degenerative sequelae of diabetes. Hence, artificial pancreata have been developed to deliver insulin continuously in direct response to physiological need, to provide the finer control of glycemia necessary for homeostasis in insulin dependent diabetes. The objective of this proposal is the demonstration that insulin can be delivered by a recently invented implantable device, the controlled release micropump (CRM) at both basal and augmented rates in dogs and thereby restore normoglycemia in diabetic dogs. Basal delivery is provided by diffusion through a rate controlling membrane from a high concentration insulin reservoir. Augmented delivery is achieved by repeated compression of a foam membrane by a piston which is the core of a solenoid wrapped around the barrel of the CRM. The device including reservoir weighs only 50 grams and consumes power only for augmented delivery. As proposed, a 2 mL reservoir could contain enough insulin for 1-2 years. With a hydrophilic membrane, there has been no difficulty with insulin precipitation typical of all other insulin pumps, causing a progressive reduction in delivery rate with time. We propose to investigate the performance of the CRM in diabetic dogs. Insulin will be delivered subcutaneously at both basal and augmented rates for various time periods from a CRM prototype which is to be mounted externally. 24 hour glucose and insulin profiles will be used to determine the in vivo delivery rate and the degree of normoglycemia that is attained. The same animals prior to pancreatectomy will be used as normal controls. With this device, diabetologists and biomedical researchers will be able to assess the potential benefits to the more than five million diabetics in North America to be derived from open loop insulin delivery systems.